Inductors can be formed or installed on integrated circuit (IC) chips for various applications. Examples include inductors in series with power rails to filter current “spikes,” e.g., from rapid switching of loads, and “LC” filters comprising various interconnects of inductors and capacitors.
One known IC chip inductor structure is the planar “zigzag” or “meander line” (hereinafter “meander”) inductor. FIG. 1 shows one conventional planar meander inductor 100, formed of a meander conductor 102 extending on the top plane of a substrate 104. However, conventional planar meander inductors as shown in FIG. 1 can have certain shortcomings. One can be area, i.e., the product of L1 and W1, the meander conductor 102 occupies on the surface of the substrate 104. Another shortcoming can be a low value of its quality factor, Q, which is the ratio of the reactance, (ω×L), to the real resistance, R, due in part to the dielectric properties of the substrate 104. The lower than preferred Q can have negative effects such as power consumption, which can reduce battery life and generate heat and, in applications such as LC filters, can reduce performance.
Another known IC chip inductor structure is a three-dimensional (“3D”) structure known as a “through-glass-via” or “TGV” 3D inductor, such as the TGV 3D inductor 200 shown by FIGS. 2A and 2B. FIG. 2A is a top view, from a direction normal to the top surface 202A of a glass substrate 202. FIG. 2B is a cross-cut projection view from the FIG. 2A cutting plane 1-1. Referring to FIGS. 2A and 2B, the TGV 3D inductor 200 employs through glass vias (TGVs) 204 as vertical segments, and top and bottom traces 206 and 208, respectively, as horizontal segments.
The TGV 3D inductor 200 can have, in some applications, a higher Q and higher inductance compared to a comparable FIG. 1 conventional planar meander inductor 100. However, the related art TGV 3D inductor 200 can have certain shortcomings. One shortcoming is that the minimum pitch (i.e., TGV-to-TGV spacing), shown as P1 and P2 on FIGS. 2A and 2B, may be larger than desired, due to fundamental aspects of TGV technology. As a result, the TGV 3D inductor 200 often occupies a larger area or volume than preferred.
Accordingly, there is a need for a high Q, low surface area IC chip inductor.